Mazzite supported catalyst

Abstract

A catalyst, method for preparing the catalyst, and method for using the catalyst having improved conversion and/or selectivity in the dehydrogenation of hydrocarbons. The catalyst being prepared by modifying and impregnating a mazzite zeolite. Modification of the original mazzite zeolite may include steps for ion-exchanging, dealuminating, physically mixing with chromic oxide, shaping, and calcining. Once modified, the mazzite zeolite may be impregnated with at least one metal selected from the group consisting of chromium, molybdenum, tungsten and oxides of these metals.

That which is claimed is: 
     
       1. A catalyst comprising: a composition formed from calcining a physical blend of chromic oxide, an inorganic binder, a peptizing agent, and a mazzite zeolite, said mazzite zeolite having been modified such that its alkali metal content is less than 0.5% by weight wherein said physical blend is impregnated with at least one metal from the group consisting of chromium molybdenum tungsten, and oxides of these metals.   
     
     
       2. A catalyst in accordance with claim 1 wherein said metal impregnated into said physical blend is chromium. 
     
     
       3. A catalyst comprising a composition formed from calcining a physical blend of chromic oxide an inorganic binder, a peptizing agent, and a mazzite zeolite, said mazzite zeolite having been modified such that its alkali metal content is less than 0.5% by weight and having been modified by dealuminating with an organic acid such that its SiO 2  to Al 2  O 3  ratio is at least 150% higher than that of the original mazzite zeolite and wherein said physical blend is impregnated with at least one metal from the group consisting of chromium, molybdenum, tungsten, and oxides of these metals. 
     
     
       4. A catalyst in accordance with claim 3 wherein said metal impregnated into said physical blend is chromium. 
     
     
       5. A process for preparing a catalyst which comprises: (a) modifying a mazzite zeolite by ion-exchanging said mazzite zeolite with an aqueous solution of an ammonium salt, such that the zeolitic product contains less than 0.5% alkali metal by weight;   (b) physically mixing the modified mazzite zeolite with chromic oxide, an inorganic binder, and a peptizing agent, such that the subsequent product is a physical blend having a consistency and texture suitable for shaping into extrudate, pellets or tablets;   (c) shaping said physical blend by extrusion, pelletizing or tableting;   (d) calcining the shaped physical blend such that the product is a modified mazzite zeolite support;   (e) impregnating said modified mazzite zeolite support with at least one metal from the group consisting of chromium molybdenum, tungsten, and oxides of these metals; and   (f) calcining the impregnated modified mazzite zeolite support.   
     
     
       6. A process for preparing a catalyst in accordance with claim 5 wherein chromium is the metal impregnated into said modified mazzite zeolite support. 
     
     
       7. A process for preparing a catalyst which comprises: (a) modifying a mazzite zeolite by ion-exchanging said mazzite zeolite with an aqueous solution of an ammonium salt, such that the zeolitic product contains less than 0.5% alkali metal by weight;   (b) modifying said mazzite zeolite by dealumination with an organic acid, such that the zeolitic product has a SiO 2  to Al 2  O 3  ratio at least 150% higher than that of the unmodified original mazzite zeolite;   (c) physically mixing the modified mazzite zeolite with chromic oxide an inorganic binder, and a peptizing agent, such that the subsequent product is a physical blend having a consistency and texture suitable for shaping into extrudate, pellets or tablets;   (d) shaping said physical blend by extrusion, pelletizing or tableting;   (e) calcining the shaped physical blend, such that the product is a modified mazzite zeolite support   (f) impregnating said modified mazzite zeolite support with at least one metal selected from the group consisting of chromium, molybdenum, tungsten, and oxides of these metals; and   (g) calcining the impregnated modified mazzite zeolite support.   
     
     
       8. A process for preparing a catalyst in accordance with claim 7 wherein said organic acid is oxalic acid. 
     
     
       9. A process for preparing a catalyst in accordance with claim 7 wherein chromium is the metal impregnated into said modified mazzite zeolite support. 
     
     
       10. A process for preparing a catalyst in accordance with claim 9 wherein said ammonium salt is ammonium nitrate, said inorganic binder is an alumina binder, said peptizing agent is an aqueous solution of acetic acid, and said acid is oxalic acid.